1. Field
This invention relates to polymers which are surface modified by attachment of compounds having groups absorbable into said surface and reactive groups by absorption of the compatible groups into the surface area of the polymers.
2. Prior Art
Polymer surfaces, particularly hydrophobic polymer surfaces, have been treated in various ways to render the polymer surface nonthrombogenic so that plastic materials may be utilized with less risk in the field of artificial organs and prosthetic devices.
One such surface modification treatment is described by Froehling et al, Uptake of Tridodecylmethylammonium Chloride by PVC, Journal of Applied Polymer Science, Vol, 21, 2855-2859 (1977). The molecules to be absorbed appear to repell each other, limiting the number of groups which can be attached to a given surface area of substrate. Quaternary ammonium salt, i.e., tridodecylmethylammonium chloride (TDMAC) has been absorbed into a substrate to provide an ion exchange capacity which can be used to ionically bond heparin. This general approach is also disclosed in U.S. Pat. No. 3,617,344 of Leininger et al. A similar technique is described in U.S. Pat. No. 3,549,409 of Dyck et al wherein a polyvalent metal salt is absorbed upon a plastic surface to provide sites for heparinization.
Another approach has been to synthesize polymers which directly absorb heparin, thus enabling construction of plastic articles which may be directly heparinized. Modified poly-amido-amine block copolymers have been prepared; A New Nonthrombogenic Polymeric Material Ferruti and Provenzale, Transplantion Proceedings, Vol. VIII, No. 1, March 1976.